1. Technical Field
Embodiments described herein relate generally to a sanitary washing device, and more particularly to a sanitary washing device for washing with water the “bottom” and other parts of a user seated on a sit-down toilet stool.
2. Background Art
When a washing nozzle for private parts washing squirts wash water at the private parts, at least part of the washing nozzle is exposed (advanced) outside from the casing installed with prescribed functional components including the washing nozzle and a hot water tank. Hence, dirt and dirty water may be attached to the washing nozzle. In this context, there is a sanitary washing device which cleans away dirt and dirty water attached to the washing nozzle before and/or after private parts washing. This keeps the washing nozzle clean.
However, in a humid environment such as a toilet room, even after dirt and dirty water attached to the washing nozzle are cleaned away, bacteria may grow on the washing nozzle over time. More specifically, bacteria such as methylobacteria, called pink slime, and black mold grow on the bowl surface of the toilet stool. Such bacteria may be attached to the washing nozzle and multiplied thereon. Multiplication of bacteria results in an aggregation of bacteria and their secretion (slime, black stain), called biofilm. The biofilm is difficult to remove by the normal nozzle cleaning as mentioned above.
In this context, Japanese Patent No. 3487447 proposes a sanitary washing device. In this sanitary washing device, an electrolytic cell is connected to the flow channel for supplying wash water. The electrolytic cell produces water containing hypochlorous acid. This water is regularly supplied to sterilize the washing nozzle so as to avoid biofilm formation. On the other hand, International Publication Pamphlet WO 95/32922 proposes an electrolyzing device and electrolyzing method for producing water containing hypochlorous acid. In the electrolyzing device and electrolyzing method described in WO 95/32922, running water containing chlorine ions flows into an electrolytic cell, and is electrolyzed after being heated. Hence, the generation efficiency of free chlorine can be increased.
Thus, bacteria attached to the washing nozzle and bacteria in the flow channel to the washing nozzle are sterilized, and formation of biofilm is suppressed. However, for instance, some mold is not sterilized by the sterilization process of several seconds and may partly survive in the flow channel. Furthermore, after performing the sterilization process, if the user does not use the sanitary washing device for some time, such mold may multiply.
In some devices, the sterilization process for sterilizing the washing nozzle with sterilizing water containing hypochlorous acid or silver ions is performed during a sequence of operations. For instance, in the case of no use for a long time during travels and the like, bacteria are intensively multiplied and may cause clogging in the drain pipe with a small diameter. In view of this situation, JP-A-2001-279745 discloses a human body washing device equipped with a silver ion electrolytic device. In this device, silver ion electrolytic water is passed and filled throughout the water channel on the downstream side of the silver ion electrolytic device. When the non-use state continues for a long time, the power of silver ion electrolytic water for suppressing multiplication of bacteria may be weakened. To prevent this, the human body washing device equipped with a silver ion electrolytic device described in JP-A-2001-279745 renews silver ion electrolytic water at regular intervals for passing water.
On the other hand, Japanese Patent No. 3487447 discloses a private parts washing device. In this device, the private parts washing water is clean water or gray water. The nozzle cleaning water exhibits stronger disinfectant or sterilizing property than the private parts washing water. The nozzle cleaning device includes a nozzle cleaning water producing unit for changing the property of clean water or gray water to produce the nozzle cleaning water. In the private parts washing device described in Japanese Patent No. 3487447, liquid chemical is used to clean the nozzle device. Hence, as compared with the conventional cleaning by showering only the wash water, dirt can be effectively removed. Furthermore, the effect of sterilizing and removing bacteria is highly expected.
However, in the human body washing device equipped with a silver ion electrolytic device described in JP-A-2001-279745, the extent of the weakening of the power of silver ion electrolytic water for suppressing multiplication of bacteria due to prolonged non-use state generally depends on the amount of remaining bacteria and the like. In the device described in JP-A-2001-279745, when the human body sensing device senses a user, the silver ion electrolytic water is drained. Subsequently, with the power feed to the silver ion electrolytic device stopped, heated water is discharged from the water discharge port for human body washing. Then, the sterilizing power may decrease, and bacteria may multiply. Thus, the hot wash water may be contaminated with bacteria.